Side Tournaments At Worlds

Having never been to Worlds before I am only assuming side events are being run during the weekend outside of the prerelease somewhat like Nationals. If there are side event tournaments at worlds since they are not sanctioned (or are they sanctioned) will Furious Fist be legal?

Asked over on a Facebook group with several firm "No's." The reason I had to ask was that the wording left that three week window only to sanctioned events. The furthering of that was fun events run by OP are close enough to sanctioned in this regard.